Upstream of Virginia Water (village) where the River Bourne exits the lake After gathering a number of streams flowing from north, south and west into
Virginia Water Lake the stream coalesces into one large stream for the rest of its course. The lake is largely created by a steep boulder cascade with eastern embankments close to car parks at the side of Windsor Great Park, on the
A30 London Road. The Chertsey Bourne flows through the north of the landscaped
Wentworth Estate, a residential 'golfside' mansions estate dating to periods since the 1920s, where a further weir creates the much smaller Wentworth Pond which is by the
Wentworth Club clubhouse. Before Wellington Bridge across the course, the Wentworth Brook rising in
Sunningdale Golf Club joins. After this the brook is less exposed to view forming a wide, wooded divide in
Virginia Water lined with a walk. The land either side of the River Bourne below the Lake and west of
Virginia Water railway station is owned by
Runnymede Borough Council as trustees of the Cabrera Trust, named after Spanish noble Ramòn Cabrera who owned and developed a wide landscape at Wentworth. ;Early Bridges The
bridge nearest the source is an old
girder bridge. It is a curiosity and its origin is obscure. Old maps show the valley as wet pastureland, probably suitable for
cattle, so a strong bridge would have been necessary. Near the second bridge downstream from the source, there is a colony of
mandarin ducks. They were introduced to the River Bourne in 1929–30. The colony is probably the largest in the
United Kingdom and is of international significance due to the rapid decline of
mandarin ducks in its native
Asia.
Downstream of Virginia Water (village) At Thorpe Green, a green, road and line of houses beneath Virginia Water station, the river forms the southern border of
Thorpe and the northern border of
Lyne. During its passage, the northern bank of the Bourne receives more sun than the south. This affects the
microclimate as there are seasonal
frost pockets and areas of high humidity which impacts the
vegetation. The Bourne passes into
Chertsey and adjoins Chertsey Meads before entering the grounds of
St George's College, formerly
Woburn Park, close to the Thames in
Addlestone. Here, now slow-flowing, as a small river, it joins with the
Addlestone branch. Combined, these briefly create a back-gardens feature with a deep, vertical metal-lined channel. This joins the
River Thames within below its southernmost weir, in one of its channels bypassing
Shepperton Lock beside Hamm Court,
Addlestone close to the border with
Weybridge which is marked by the
River Wey that joins a further downstream of this. The longest tract of public land is upstream at and by
Virginia Water Lake, particularly beyond that when
Windsor Great Park is open, in this section it include walks in two parks in
Chertsey. The river creates access for small motorboats and canoes for the 20 properties in its lowest reach at Hamm Court. Only the lower section below a weir is
canalised, the remainder is natural bank, forming a minor habitat for the
European water vole. The middle course of the Bourne passes under the
M3 motorway three times in a short space. In the midst of which the
M25 also crosses it. ==Surrounding Soil, Elevations and Rainfall==